The proposed research is designed to continue the clinical evaluation of the efficacy of Dialectical Behavior Therapy (DBT) with chronically parasuicidal women with borderline personality disorder (BPD). Previous research has indicated the effectiveness of standard DBT, which consists of concurrent individual psychotherapy and group behavioral skills training. What remains unclear is whether these results can be replicated under more tightly controlled conditions (e.g., guaranteeing that all subjects in the control group receive at least some psychotherapy). The proposed treatment study addresses this question and aims to 1) replicate the initial study comparing standard DBT to the control condition of community treatment-as-usual (TAU); 2) evaluate whether gains in DBT are due characteristics of DBT rather than a) general factors associated with receiving any psychotherapy, b) availability of affordable treatment, c) number of hours o individual psychotherapy offered or received, d) total hours of outpatient therapy received or d) years of therapist clinical experience and 3) analyze the association of specific therapy characteristics to treatment outcome. In the proposed study, 100 females with a history of repeated parasuicides and a diagnosis of BPD will be randomly assigned to one of two conditions: Standard DBT or TAU. Outcome measures will focus on suicidal behaviors, therapy-interfering behaviors (e.g. treatment compliance), psychiatric hospitalization, affect, social functioning and global functioning. Subjects will be assessed at pre-treatment, at 4-month intervals during the treatment year and at 4-month intervals for one year following treatment, for a total of seven assessments. Additional daily patient ratings and weekly patient and therapist ratings for subjects in the DBT condition will be obtained.